1. Field of the Invention
The invention concerns a hydroalcoholic microemulsion containing vitamin and essential oils which exhibits excellent physical stability and clarity.
2. The Related Art
A clear, skin care product that contains water and alcohol conveys a sense of purity to the consumer. The presence of alcohol also imparts quick drying and cooling sensation characteristics. The use of alcohol is also important for many therapeutic products as it will solubilize certain organic acids such as salicylic acid. Antimicrobial activity is a further benefit.
Many therapeutic cosmetic ingredients are water-insoluble, e.g. vitamins and essential oils. These water-insoluble ingredients require them to be emulsified into a water phase in order to be effectively delivered to the skin. Emulsions tend to be opaque or white because of the large droplet size. Microemulsions consist of micelles of a monolayer of surfactant surrounding an oil droplet. These micelles are small enough so that they do not appreciably diffract light producing a clear product. Alcohol is known to prevent the formation of both emulsions and micelles; indeed, alcohol is commonly used to break emulsions. Formation of a microemulsion that is stable in a hydroalcoholic system is, therefore, quite difficult. Furthermore, the vitamin oils, in particular, are very difficult to form microemulsions with.
Accordingly, it is an object of the present invention to provide a hydroalcoholic microemulsion that is both quick drying and imparts a cooling sensation.
It is another object of the present invention to provide a hydroalcoholic microemulsion wherein the micelles are sufficiently small so they do not appreciably diffract light, thereby producing a clear product.
It is still another object of the present invention to provide a hydroalcoholic microemulsion wherein vitamin oils and terpenes are emulsified to achieve not only a clear product but one that is storage stable.
These and other objects of the present invention will become more readily apparent from consideration of the following summary, detailed description and examples which follow.